From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34774) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dsnPj-00069P-Ex for qemu-devel@nongnu.org; Fri, 15 Sep 2017 06:00:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dsnPg-0001Sr-Bm for qemu-devel@nongnu.org; Fri, 15 Sep 2017 05:59:59 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44698) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dsnPg-0001SR-3W for qemu-devel@nongnu.org; Fri, 15 Sep 2017 05:59:56 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7F16DC04B927 for ; Fri, 15 Sep 2017 09:59:54 +0000 (UTC) Message-ID: <1505469579.4717.5.camel@redhat.com> From: Mohammed Gamal Reply-To: mgamal@redhat.com Date: Fri, 15 Sep 2017 11:59:39 +0200 In-Reply-To: <20170915020701.GK3617@pxdev.xzpeter.org> References: <1505420311-23744-1-git-send-email-mgamal@redhat.com> <96709f6f-b4c8-f752-fd0d-f73de9023bcc@redhat.com> <20170914203138.GD23492@localhost.localdomain> <20170915020701.GK3617@pxdev.xzpeter.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] amd_iommu: Return error on machines with no PCI List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Xu Cc: Eduardo Habkost , pbonzini@redhat.com, Thomas Huth , qemu-devel@nongnu.org, mst@redhat.com On Fri, 2017-09-15 at 10:07 +0800, Peter Xu wrote: > On Thu, Sep 14, 2017 at 05:31:38PM -0300, Eduardo Habkost wrote: > > On Thu, Sep 14, 2017 at 10:24:23PM +0200, Thomas Huth wrote: > > > On 14.09.2017 22:18, Mohammed Gamal wrote: > > > > Starting the following command line causes a segfault > > > > qemu-system-x86_64 -S -machine isapc,accel=kvm -device amd-iommu > > > > > > > > This is due to the fact that the machine type 'isapc' doesn't have > > > > a PCI bus, while amd_iommu doesn't check if the machine has PCI support > > > > and subsequently does a null-pointer access. AMD IOMMU shouldn't even work > > > > if the target machine doesn't have PCI. > > > > > > > > Add a check for PCI on the given machine type and return an error if PCI > > > > is not supported. > > > > > > > > Signed-off-by: Mohammed Gamal > > > > --- > > > > hw/i386/amd_iommu.c | 7 +++++++ > > > > 1 file changed, 7 insertions(+) > > > > > > > > diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c > > > > index 334938a..9a667b7 100644 > > > > --- a/hw/i386/amd_iommu.c > > > > +++ b/hw/i386/amd_iommu.c > > > > @@ -1153,6 +1153,13 @@ static void amdvi_realize(DeviceState *dev, Error **err) > > > > } > > > > > > > > bus = pcms->bus; > > > > + > > > > + if (!bus) { > > > > + error_setg(err, "Machine-type '%s' does not support PCI", > > > > + mc->name); > > > > + return; > > > > + } > > > > + > > > > s->iotlb = g_hash_table_new_full(amdvi_uint64_hash, > > > > amdvi_uint64_equal, g_free, g_free); > > > > > > > > > > > > > > Patch looks fine to me, but I think it would also be sufficient to > > > change the check at the beginning of the function to test "if (!pcms || > > > !pcms->bus)" instead of just "if (!pcms)" ... the error message > > > "Machine-type 'xxx' not supported by amd-iommu" is also adequate if > > > there is no PCI bus available on the system. > > > > I agree this would be much simpler. > > Even, shall we move the pcms && bus check into x86_iommu_realize() > directly? Then we will only need one single patch for Intel/AMD, and > it's also a cleanup. Thanks, Although it's more straight forward to do the checks in amdvi_realize() and vtd_realize() at the moment, I think moving the checks to x86_iommu_realize() would be better on the longer term. I will be sending out a new patch with this change shortly. Regards, Mohammed